Direct Electrical Heating of Reactive Systems

This application is a continuation of U.S. patent application Ser. No. 18/142,933, filed May 3, 2023, which is a continuation of U.S. patent application Ser. No. 17/532,571, filed Nov. 22, 2021, which issued on Jul. 11, 2023 as U.S. Pat. No. 11,697,099, the entire disclosures of which is hereby incorporated by reference for all purposes.

Provided herein are methods and systems for direct electrical heating of catalytic reactive systems. Also provided herein are methods for conducting catalytic reactions comprising a system utilizing direct electrical heating.

Typically, a reaction system for a catalytic reaction comprises arranging a catalyst within a reactor and directing a fluid (i.e. a liquid or gas) through the reactor where the catalytic reaction takes place. The product of the catalytic reaction is then withdrawn from the reactor and collected as a final product or directed for further processing.

Certain catalytic reactions require the presence of external heat to promote the reaction and or efficiently produce the desired product. Many systems of heating a catalytic reactor are known. For example, fired heating. Fired heating typically is comprised of either a direct fired heating system or an indirect fired heating system. In either fired heating system, the heat is typically generated by combustion of a hydrocarbon.

However, a problem exists when the heat supplied to a reactor system is provided by a fired heating system. For example, in a catalytic reaction system comprising reactor tubes, the fired heating of the reactor tube often results in uneven temperature gradients along the tube. Uneven temperature gradients along the tube can lead to premature tube failure and adversely impact throughput, catalyst life, and yield/quality of the desired product. Additionally, where multiple reactor tubes are present, there is typically a temperature differences between the tubes. Temperature differences between the reaction tubes in the same reactor system results in non-optimal throughput, and yield/quality of the desired product.

Furthermore, all fired heaters are subject to typical wear and tear which will ultimately lead to deterioration in the fired heater energy efficiency. Where the fired heater comprises combustion of hydrocarbons or other materials that emit greenhouse gases such as CO, this deterioration in fired heater energy efficiency contributes to increases in greenhouse gases released from the fired heater.

Accordingly, there remains a need in the art to develop reaction systems and processes wherein heat is provided to the catalytic reaction such that a more even temperature gradient is observed along the surface of the reactor. There also remains a need in the art for the development of heating methods for catalytic reaction processes where the emission of greenhouse gases or other pollutants are minimized or eliminated.

The present disclosure is directed to a method of heating a reactor system wherein the reactor system comprises at least one reactor tube having a catalyst disposed therein and wherein the reactor tube comprises at least one electrically conductive surface. The method comprises electrically isolating the reactor tube from other electrically conductive components of the reactor system; providing electrical energy to the at least one electrically conductive surface on the reactor tube; and adjusting a current level of the electrical energy provided to the at least one electrically conductive surface to control the temperature of the reactor tube and the catalyst disposed therein.

The present disclosure is also directed to a method of heating a reactor system comprising a plurality of reactor tubes having a catalyst disposed therein and wherein each of the plurality of reactor tubes comprise at least one electrically conductive surface. The method comprises electrically isolating each of the plurality of reactor tubes from the other electrically conductive components of the reactor system; providing electrical energy to the at least one electrically conductive surface on each of the plurality of reactor tubes; and controlling the temperature of each of the plurality of reactor tubes and the catalyst disposed therein by adjusting a current level of the electrical energy provided to the at least one electrically conductive surface.

A reactor system embodying aspects of the present disclosure comprises one or more reactor tubes each having a catalyst disposed therein as well as inflow and outflow pipes through which fluid enters and exits the reactor tube, respectively. The system also includes insulative gaskets between the reactor tube and inflow and outflow pipes to electrically isolate the reactor tube from other electrically conductive components of the reactor system. An electrical power source is configured to energize at least one electrically conductive surface on the reactor tube with an adjustable current level of electrical energy to control the temperature of the reactor tube and the catalyst disposed therein.

Other objects and features will be in part apparent and in part pointed out hereinafter.

Corresponding reference characters indicate corresponding parts throughout the drawings.

The present disclosure is directed to a method of heating a reactor system comprising a reactor having a catalyst disposed therein, wherein the reactor and the catalyst are heated by providing electrical energy to at least one electrically conductive surface on the reactor.

Referring to, a reactor systemembodying aspects of the present disclosure includes a reactorhaving one or more reactor tubes (not shown) through which material flows into the reactor at an inletand flows out of the reactor at an outlet. In the illustrated embodiment, an electrical power supplyis configured to energize a conductive surface (not shown) of each reactor tube. During operation, a controlleradjusts a current level of electrical energy supplied to the conductive surface by the power supply.

shows a top-down view of the reactorcomprising a plurality of reactor tubes, each having a catalyst (not shown) disposed therein. The circles represent individual reactor tubescontained within a thermally insulated housing. In addition, each of the individual reactor tubesare electrically isolated from other electrically conductive elements in reactorand from each other.

shows a side view of one reactor tubeas described above. The material to be contacted with a catalystis introduced through the top of reactor tubevia the inlet, contacts the catalyst particles present within reactor tube, and exits the bottom of reactor tubevia the outlet. Electrical connectorsfrom the electrical power supplyare shown inconnected to the left side of reactor tube. The electrical connectorsare configured such that they are capable of supplying electrical energy from electrical power supplyto an electrically conductive surface (e.g., the wall of reactor tubeor an external conductor electrically coupled to reactor) present on reactor tube. Finally, electrical insulatorsare shown at the top and bottom of reactor tube. The electrical insulatorsare oriented such that each reactor tubeis electrically isolated from other electrically conductive elements in the reactor system, such as piping at inletand outletas well as other reactor tubes.

One aspect of the present disclosure is directed to reactor systemcomprising a plurality of reactor tubeshaving the catalystdisposed therein. The reactor tubesand the catalystare heated by a method comprising providing electrical energy to at least one electrically conductive surface on each of the plurality of reactor tubes. It is to be understood that reactor tubeas referred to herein is interchangeable with embodiments described herein referencing reactor, when reactorcomprises a single reactor tube.

In certain aspects of the present disclosure, the reactoris electrically isolated from other electrically conductive components of the reactor systemand the temperature of the reactorand catalyst disposed therein is controlled by adjusting the current level of the electrical energy provided to the at least one electrically conductive surface on the reactor.

For example, in one aspect, the present disclosure is directed to reactor systemcomprising a plurality of reactor tubeshaving catalystdisposed therein. The plurality of reactor tubesand the catalyst are heated by a method comprising electrically isolating each of the plurality of reactor tubesfrom other electrically conductive components of the reactor system; providing electrical energy to the at least one electrically conductive surface on each of the plurality of reactor tubes; and adjusting a current level of the electrical energy provided to the at least one electrically conductive surface to control the temperature of the reactor tubeand the catalystdisposed therein.

A reaction system for a catalytic reaction comprises arranging a catalyst within reactorand directing a fluid (i.e. a liquid or gas) through the reactorwhere the catalytic reaction takes place. The product of the catalytic reaction is then withdrawn from the reactorand collected as a final product or directed for further processing. In an embodiment, reactorof the catalytic reaction may comprise a fixed or fluidized reactor. In a fixed bed reactor, the catalyst is maintained within a defined space of the reactor and the fluid flows over the catalyst and/or through the interstitial regions between the catalyst particles. In a fluidized bed reactor, the fluid is introduced into the reactor at a sufficient velocity so as to fluidize the catalyst or catalyst particles. Fluidized bed reactors may maintain the catalyst within a defined region of the reactor (e.g., between two screens) so that the catalyst is not lost during the course of the process. One example of a catalytic reaction system is a system comprising one or more reactor tubes wherein a catalyst material is disposed therein. In other embodiments, the reactor bed system may comprise a screening step to remove the catalyst from the fluid present in the reactor.

Certain catalytic reactions require the presence of external heat to promote the reaction and or efficiently produce the desired product. Previously, heat was provided to a catalytic reaction by either a direct fired heating system or an indirect fired heating system.

In a direct fired heating system, heat is supplied directed to the reactor. In an indirect fired heating system, heat is generated and transferred to an intermediate fluid. The intermediate fluid is then transported to the reactor to provide the heat. However, fired heating systems often result in uneven temperature gradients along the reactor. This non-uniform temperature along the surface of the reactor typically contribute to premature reactor failure and adversely impacts throughput, catalyst life, and yield/quality of the desired product. When the catalyst disposed within the reactor is subjected to uneven heating, the catalyst life is also greatly reduced. Additionally, fired heaters are subject to typical wear and tear which will ultimately lead to a decrease in the fired heater energy efficiency. Since most fired heaters generate heat by combustion, such as combustion of a hydrocarbon or other materials that emit greenhouse gases such as CO, this deterioration in fired heater energy efficiency contributes to an increase in greenhouse gases released and/or generated from the fired heater. In certain instances, this deterioration in efficiency may cause the efficiency to fall outside of the bounds of the design conditions.

A solution to this problem has been discovered by the method and reaction system of the present disclosure. In the present disclosure, the fired heating system is replaced with a direct electrical heating system. Furthermore, the direct electrical heating system uses the reactoras the heating element by providing electrical energy to an electrically conductive surface on the reactor. The current provided to the reactorcan be modulated to control the temperature of the reactor and/or catalyst within the reactor and maintain a suitable temperature gradient. Thus, direct electrical heating of the reactorallows for a finer and more accurate control of the temperature of the reactor. This results in improvements in the yield/quality of the desired product, an increase in throughput, extended catalyst life, etc.

A system comprising a plurality of reactors (e.g., reactor tubes) may be subjected to individual electrical heating of each reactorby providing electrical energy to the electrically conductive surface of each individual reactor. This allows for a high degree of control of each reactorand a much smaller difference in the temperature between individual reactors. A more uniform distribution of temperature along a reactor wall and consistent reactor temperatures within the reaction system further benefits the process operation by creating less stress on the reactors and thus extending the reactor and catalyst life.

The ability to finely control the temperature gradient of reactorin a direct electrical heating system also allows for the possibility of dividing an individual reactor tube into two or more heating zones. This may further improve the process operations and allow for increased throughputs, yield/quality of the desired product, etc.

The problem of greenhouse gas emissions and increased pollution as a fired heater degrades can also be avoided by using an electrical heating system. Since the electrical heating system heats the reactorby providing electrical energy directly to the conductive surface of the reactor, an intermediate fluid is not needed and the energy may be provided to the reactor in a manner other than combustion of a hydrocarbon or other materials that emit greenhouse gases. Instead, the present disclosure directs electrical energy to the conductive surface of the reactor, wherein the electrical energy may originate from any renewable energy or low-emission (i.e. low carbon-emitting source) energy source. For example, the electrical energy may be sourced from a renewable energy source selected from the group consisting of a solar energy source, wind energy source, geothermal energy source, hydroelectric energy source, or tidal energy source. In one embodiment, the electrical energy originations from a nuclear power source.

Catalyst life is impacted by the poisoning of the catalyst and physical breakdown of the catalyst. Catalyst breakdown is caused primarily by expansion and contraction of the reactor, both longitudinal and radial expansion and contraction. During a catalytic reaction wherein the reactorand catalystare heated, the reactor and/or catalyst may expand or contract. For example, in a steam methane reforming process, it is typical for a 40 ft. reactor tube to expand by about 250 mm during heating, with the catalyst expanding at a significantly lower rate. As a result of this difference in expansion rates, the catalyst settles. When the reactor tube is cooled, the catalyst may be crushed during contraction of the reactor tube.

Fired heating of a reactor results in uneven temperature gradients along the reactor. The temperature gradients can be measured along the length of the reactor and/or resulting from the comparison of one side of the reactor to the opposite side. Additional hotspot can form on the reactor as a result of flame impingement or hot gas streams associated with the flame from the direct heating. Due to this uneven heating and resulting temperature gradients, the reactor undergoes uneven expansion and contraction during the heating of the reactor. This uneven expansion and contraction may be characterized as an oscillating expansion (i.e. oscillating between expansion and contraction). The resulting physical stress on the reactor from this oscillating expansion contributes significantly to the degradation of the reactor and catalyst and ultimately shortens the useable life of the reactor and/or catalyst. Premature degradation of the reactor and/or catalyst will negatively impact the throughput, yield, and/or quality of the desired product of the catalytic reaction as well as increase the maintenance and operation costs of the catalytic reaction.

In contrast, by using a direct electrical heating system of the present disclosure, it is possible to control the temperature along the reactorto ensure a more even temperature gradient both longitudinal and radially. While heating of the reactorby an electrical heating system may lead to expansion and contraction, the expansion and contraction is not of an oscillating nature. For example, the reactormay expand once during uniform heating and contract once during uniform decrease in the electrical energy provided to heat the reactor. Thus, the usable life of the reactorcan be greatly improved by limiting the cycles of expansion and contraction that the reactor experiences. Likewise, the ability of a direct electrical heating system to more uniformly heat the reactor results in a more uniform heating of the catalyst present within the reactor. By limiting the temperature oscillation that the catalyst is subjected to, the physical integrity and usable life of the catalyst is significantly increased. While there may still be temperature variation due changes in throughput or feed composition, such variations will not significantly contribute to degradation of the reactor/catalyst as compared to traditional fired heating reactor system.

For example, in one embodiment of the present disclosure, the difference in temperature between two points on the surface of the one or more reactors is about 50° C. or less, about 40° C. or less, about 30° C. or less, about 20° C. or less, about 10° C. or less, about 5° C. or less, about 4° C. or less, about 3° C. or less, about 2° C. or less, or about 1° C. or less. In another embodiment, the difference in temperature between two points on the surface of the one or more reactors is from about 50° C. to about 0.5° C., from about 40° C. to about 0.5° C., from about 40° C. to about 1° C., from about 30° C. to about 1° C., from about 20° C. to about 1° C., from about 10° C. to about 1° C., from about 5° C. to about 1° C., from about 4° C. to about 1° C., from about 3° C. to about 1° C., or from about 2° C. to about 1° C.

In an embodiment of the present disclosure comprising a plurality of reactors, the temperature difference between the hottest reactor and the coolest reactor may be about 50° C. or less, about 40° C. or less, about 30° C. or less, about 20° C. or less, about 10° C. or less, about 5° C. or less, about 4° C. or less, about 3° C. or less, about 2° C. or less, or about 1° C. or less. For example, in some embodiment, the temperature difference between the hottest reactor and the coolest reactor may be from about 50° C. to about 0.5° C., from about 40° C. to about 0.5° C., from about 40° C. to about 1° C., from about 30° C. to about 1° C., from about 20° C. to about 1° C., from about 10° C. to about 1° C., from about 5° C. to about 1° C., from about 4° C. to about 1° C., from about 3° C. to about 1° C., or from about 2° C. to about 1° C.

In addition to improving the usable life of the reactor and catalyst and demonstrating an improved throughput, yield, and/or quality of the desired product as compared to a fired heating system, the method of the present disclosure comprising a direct electrical heating system also allows for greatly improved control of the reactor system.

As explained above, a fired heating system typically comprises combustion of a hydrocarbon or transfer of the heat energy to the reactor via an intermediate fluid (i.e., a heat transfer fluid). In a fired heating system, the amount that the reactor is heated is controlled based upon the desired temperature of the reactor fluid at the exit of the reactor. There is significant delay in adjusting the temperature of the reactor because the firing rate of the combustion must be adjusted and the intermediate fluid temperature increased such that the intermediate fluid transfers the heat to the reactor and contents thereof. In this configuration, the heat transfer from the intermediate fluid is a convective heat transfer, which is typically a slower heat transfer as compared to, for example, radiant heat transfer. In this way, there may be lag time between the control input into a fired heating system and the actual change in the temperature of the reactor fluid at the exit of the reactor.

In contrast, the electrical heating system of the present disclosure comprises providing electrical energy directly to the conductive surface on the reactor. For example, in one embodiment, the reactor systemcomprises a plurality of reactor tubeshaving catalystdisposed therein and at least one electrically conductive surface on each of the plurality of reactor tubes, wherein electrical energy is provided to the at least one electrically conductive surface on each of the plurality of reactor tubes. The electrical heating system of the present disclosure controls the heat of the reactor systemby energy control (i.e., modulating the electrical energy provided to the at least one electrically conductive surface on each of the plurality of reactor tubes). Therefore, the electrical heating system of the present disclosure allows for a swift change in the reaction temperature by adjusting the electrical energy input to each reactor tube. This allows for more precise control of the reactor system, as well as the ability to more accurately maintain the temperature of each individual reactor tubeand reduce the maximum temperature difference between reactor tubesin the reactor. The electrical heating system of the present disclosure also allows for reduction in the uneven distribution of temperature within an individual tube typically observed in traditional processes, i.e. the creation of hot spots due to flame impingement on the tube or other factors that leads to the maldistribution of the heat from the combustion process.

The electrical heating system of the present disclosure also allows for a correlation to be made between the inputs of the electrical energy and the catalytic reaction product. In this way, the amount of energy input to the reactor systemcan be controlled such that no more electrical energy is introduced into the system than is required for the reaction to proceed to the desired yield or purity. In certain embodiments, it may be desirable to control the electrical energy input such that a slight excess of electrical energy is provided to the reactor system.

The control realized by an electrical heating system may provide exceptional improvements over a fired heating system. For example, a reactor system comprising an indirect fired heating system may require 20 minutes or longer between adjustment of the temperature profile in the heater and the desired change in the reactor system. However, reactor systemcomprising an electrical heating system may require less than 1 minute between adjustment of the energy input to the reactorand the desired change in the reactor system. This not only provides improved the safety of the reactor systembut allowed for a more efficient process as compared to systems comprising a fired heater.

The electrical energy provided to the at least one electrically conductive surface of the reactoror plurality of reactorsmay be from a plurality of electrical energy sources. In certain embodiments, at least a portion of the electrical energy is provided by a renewable energy source or low carbon-emitting source. For example, the energy may be provided from a nuclear power source. In other embodiments, the electrical energy is provided solely by a renewable energy source. The renewable energy source may be, for example, selected from the group consisting of a solar energy source, wind energy source, geothermal energy source, hydroelectric energy source, or tidal energy source.

The reactorused in the reactor systemof the present disclosure may be any suitable reactor. For example, the reactor may be a fixed or fluidized reactor. In certain embodiments, the reactor of the direct electrical heating system of the present disclosure comprises a plurality of reactor tubes. For example, a plurality of fixed bed reactor tubes. Although reference is made herein to an embodiment comprising a plurality of reactor tubes, it will be understood that the reactor system and methods of the present disclosure are equally applicable to systems comprising other types of reactors.

The reactor(s)are designed or selected such that each reactor has at least one electrically conductive surface for the application of electrical energy. In certain embodiments, each of the plurality of reactor(s) comprise an electrically conductive material such that at least one surface of the reactor is electrically conductive. For example, in some embodiments, the materials of construction of the reactor(s) comprise an electrically conductive material such that at least one surface of the reactor is electrically conductive. In another embodiment, the reactor(s) comprise an electrically conductive material affixed to one or more surface of the reactor.

The electrically conductive material may comprise an electrically conductive metal or alloy. For example, the metal or alloy may be selected from the group consisting of gold, silver, copper, aluminum, nickel, tin, brass, iron, platinum, palladium, molybdenum, tungsten, chromium, niobium, chromium, alloys thereof, and combinations thereof. In certain embodiments, the metal or alloy is selected from the group consisting of gold silver, copper, nickel, tin, chromium, niobium, alloys thereof, and combinations thereof. In still further embodiments, the metal is selected from the group consisting of nickel, chromium, niobium, alloys thereof, and combinations thereof. In certain embodiments, the metal is a nickel alloy wherein the alloy further comprises chromium, iron, molybdenum, and/or copper. In still further embodiments, the electrically conductive material may comprise an electrically conductive ceramic.

In one embodiment, the one or more reactor(s)comprise an electrically conductive metal such that at least one surface of each reactor is electrically conductive. Each rector tube may comprise, for example, about 25 wt. % or greater, about 30 wt. % or greater, about 35 wt. % or greater, about 40 wt. % or greater, about 45 wt. % or greater, about 50 wt. % or greater, about 55 wt. % or greater, about 60 wt. % or greater, about 65 wt. % or greater, about 70 wt. % or greater, or about 75 wt. % or greater of total electrically conductive metal. In certain embodiments each rector comprises from about 25 wt. % to about 75 wt. %, from about 30 wt. % to about 70 wt. %, from about 35 wt. % to about 70 wt. %, from about 40 wt. % to about 70 wt. %, from about 45 wt. % to about 70 wt. %, from about 50 wt. % to about 70 wt. %, from about 55 wt. % to about 65 wt. %, or from about 60 wt. % to about 65 wt. % of total electrically conductive metal.

In one embodiment, each reactorcomprises from about 5 wt. % to about 40 wt. %, from about 10 wt. % to about 35 wt. %, from about 15 wt. % to about 30 wt. %, or from about 20 wt. % to about 30 wt. % of chromium.

In some embodiments, each reactorcomprises from about 5 wt. % to about 50 wt. %, from about 10 wt. % to about 45 wt. %, from about 15 wt. % to about 40 wt. %, from about 20 wt. % to about 40 wt. %, from about 25 wt. % to about 40 wt. %, or from about 30 wt. % to about 40 wt. % of nickel.

In certain embodiments, each reactorcomprises from about 0.5 wt. % to about 5 wt. %, from about 0.5 wt. % to about 4 wt. %, from about 0.5 wt. % to about 3 wt. %, from about 0.5 wt. % to about 2 wt. %, or from about 1 wt. % to about 2 wt. % of niobium.

In other embodiments, each reactorcomprises from about 0.5 wt. % to about 5 wt. %, from about 0.5 wt. % to about 4 wt. %, from about 0.5 wt. % to about 3 wt. %, from about 0.5 wt. % to about 2 wt. %, or from about 1 wt. % to about 2 wt. % of molybdenum.

In still further embodiments, each reactorcomprises a nickel alloy wherein the alloy further comprises chromium, iron, molybdenum, and/or copper and wherein the reactor comprises from about 0.5 wt. % to about 5 wt. %, from about 0.5 wt. % to about 4 wt. %, from about 0.5 wt. % to about 3 wt. %, from about 0.5 wt. % to about 2 wt. %, or from about 1 wt. % to about 2 wt. % of the nickel alloy.

Each of the reactorsof the reactor systemand methods of the present disclosure are insulated and/or isolated to ensure that the electrical energy provided to the at least one electrically conductive surface of the reactor does not freely flow to other parts of the reactor system. In an embodiment comprising a plurality of reactors, each of the plurality of reactors are electrically isolated from the other electrically conductive components of the reactor system. For example, each of the plurality of reactors may be electrically isolated from one another and the other electrically conductive process equipment present in the process.

The reactor(s)may be electrically isolated, for example, by refractory materials. In certain embodiments, the reactor(s)may be electrically isolated by a material selected from the group consisting of ceramics, nylon, polystyrene, polyvinylchloride (PVC), silicon, rubber, glass, and combinations thereof.

In one embodiment, an electrical insulator is placed at the physical connection point between the one or more reactors. In another embodiment, the reactor systemcomprises a plurality of reactorsand electrical insulators are positions such that no single reactor is in contact with another reactor. In still further embodiments, the reactor systemcomprises a plurality of reactorsand the plurality of reactors are electrically insulated from the remainder of the process equipment., explained in further detail below, illustrates a reactor system comprising 16 reactor tubes arranged such that each reactor tube is electrically insulated and the entire reactor system is surrounded by an insulating wall material.

The material used to electrically insulate and/or isolate each of the reactors of the reactor system may be any suitable insulating/isolating material. For example, the insulating/isolating material may be selected from the group consisting of ceramics, nylon, polystyrene, polyvinylchloride (PVC), silicon, rubber, glass, and combinations thereof. In certain embodiments, the insulating/isolating material may be selected from the group consisting of refractory materials, ceramics, and glass.